Breastpumps for use by nursing mothers are well known. They allow the nursing woman to express the breastmilk as necessary or convenient, and further provide collection of breastmilk for later use. For some mothers, breastpumps may be a necessity, such as when the child has suckling problems. A breastpump may also be necessary for the mother who has problems with excessive or deficient milk production, or who has soreness, deformation or injury of the mammilla.
Breastpumps for single-breast pumping and double-breast pumping are both commonplace. Single-breastpumps by their nature pump only one breast at a time. Double-breastpumps have the advantage of pumping both breasts at the same time. Double-breastpumps typically are motor driven, being either battery or electrically driven.
In known equipment of this type, two breastpump shields are connected by air suction lines to a pressure chamber of a suction pump assembly. A low (or reduced) pressure is created inside the chamber by either a reciprocating piston, diaphragm or the like within the suction unit, thereby creating a suction (or vacuum) within the breastpump shields. In these types of known breastpumps, suction pressure is typically applied to the breasts only during the suction (intake or pull) stroke of the piston or diaphragm. In addition, known breastpumps of this type apply suction pressure to both breasts simultaneously (i.e., in "parallel"). This is ordinarily accomplished using a single output from the suction source which is then split between the two breastshields.
It has now been determined that alternating suction on the two breasts offers several advantages, including a significant reduction in the time required for breast pumping. Applicants are not aware of any breastpump in the prior art which has been developed for double-breast pumping which alternates a suction stroke on two breasts in double-pumping mode. It is known, however, to alternate a compression (increased pressure) stroke between two breasts being pumped, but with a continuous vacuum to the breasts, as shown in U.S. Pat. No. 4,607,596.